The present invention relates generally to a machine and method for forming cans and similar articles into rectangular, self-sustaining bales for re-cycling.
In current can crushing machines, such as that described in U.S. Pat. No. 4,601,238 of Davis et al., a quantity of cans is fed into a rectangular baling chamber and a large, heavy piston is moved by an hydraulic drive ram back and forth in the chamber to compress the cans to a block or bale of the desired size. In order to ensure that the block is of a standard weight and size, the cans are normally weighed before feeding them into the baling chamber. Another option is to use the compacting piston to sense through the pressure it has to exert on the cans whether the correct can density has been reached. In other words, the cans are compressed until a predetermined compression pressure is reached. One problem with this option is that cans fed into the baling chamber will be in a wide range of different conditions, from non-compacted to partially compacted and completely compacted. The compacting piston is heavy and slow, and typically requires a number of strokes to compress the mass of cans to the predetermined pressure. At this point, the bale may or may not be the correct size, in view of the different initial degrees of compaction of the cans. If the bale is not the right size, the piston must be retracted again to allow more cans to fall into the chamber, and these must be compressed with the original cans until a bale of the correct dimensions is made.
Since the piston must apply a substantial compressive force, its hydraulic drive has a very large oil capacity and requires a considerable amount of time to make each thrust. A large number of thrusts are required to perform the initial compaction, making the can baling process slow and therefore relatively expensive.